I like my 757Ai video wise. Does everything almost... Old firmware is only progressive on NTSC. There is some serious post processing capabilities that really improve PQ.
My test was always "The Wedding Singer" as it has some terrible block artifacts that expose bad players. Never seen them with the 757Ai.
As for SACD I have heard nothing like it, got a pair of B&W 603s3's and sounds just amazing hooked up to a STR-DB940 Sony Av amp. I suspect the speakers are a big plus though...
If there is anything you want to know about the Pioneer, let me know.
Thanks for the reply Noo - I already have a 757 myself, and like yours it is one of the original ones, with only NTSC progressive scan. I wondered if getting a Marantz 7600 would be a useful swap now that I have a plasma with an HDMI input (as my Pioneer doesn't have one of those either). I can't yet make use of the firewire for music output, as my amp doesn't have that feature, and I don't plan to change my amp until there is some stability with the new sound formats.